Electrical connectors and other similar electrical components often include electrical conductors embedded within an insulating block to isolate the conductor from the surrounding environment. Embedding the conductor within a block protects the conductor from damage, and also prevents the delivery of an unintended electrical shock. Electrical isolation is particularly important when the connector is to be coupled to an implantable medical device such as a pacemaker or defibrillation system. Electrical connector assemblies are coupled to a hermetically sealed housing of an implantable medical device that encloses internal circuitry such as a hybrid circuit board and one or more batteries. Such a medical device connector assembly is adapted for receiving medical leads used with the implantable medical device.
Methods for forming electrical connector assemblies having conductors embedded within an insulating block may include injection molding techniques or thermoset casting techniques. An improved method for forming an implantable medical device connector assembly with embedded conductors is generally disclosed in U.S. Pat. No. 6,817,905 (Zart et al.), hereby incorporated herein by reference in its entirety. The method generally includes forming a core portion using either an injection molding process or a machining process. The core portion is fitted with electrically conductive components and submitted to a subsequent overmold process in which a second shot of thermoplastic material is injected into the mold. This improved process allows complex connector structures to be manufactured in a fast production cycle.
In the implantable medical device industry, standards have been developed for lead connector assemblies which are adapted to mate with the device connector assembly. In past practice, lead connector assemblies have included sealing members positioned around insulating structures located between lead connector terminals. The sealing members prevent the ingress of body fluids into a connector bore thereby electrically isolating the connector circuit elements. Ingress of body fluids may otherwise lead to a short circuit between separate connector circuits.
A new lead connector assembly industry standard, the IS4 connector assembly, includes four in-line lead terminals that are separated by insulating structures but do not include sealing members. A device connector assembly adapted to receive the IS4 lead connector assembly should therefore incorporate sealing members to provide electrical isolation of the connector circuits. Such sealing members are typically formed as rings fabricated from a supple, biocompatible material, such as silicone rubber. The sealing members are adapted to mate with insulating structures of the IS4 lead connector assembly to form a fluid-resistant seal.
The supple sealing members, however, may not withstand high pressure or high temperature processes which may be used during manufacture of the connector assembly, such as the overmolding process disclosed in the '905 Zart patent. A device connector assembly that incorporates sealing members for accommodating lead connectors without sealing members and withstands high pressure and/or high temperature manufacturing processes without compromising the integrity of the connector assembly is therefore needed.